FR2705567A1 - Microparticles, preparation process and application to dressings - Google Patents

Abstract

The invention relates to microparticles comprising a polymeric component and an agent having pharmacological activity, to a process for their preparation and to occlusive dressings used for skin patch tests comprising such particles.

Description

MICROPARTICLES, PROCESS FOR THE PREPARATION

AND APPLICATION TO DRESSINGS

  The present invention relates to a microparticle, to methods for manufacturing microparticles, to the use of these microparticles in occlusive patch transdermal tests ("patch tests"), to the use of microparticles as a delivery system. agents active in animals or humans, a diagnostic method using the microparticles and a test patch or dressing in which the microparticles are incorporated. The microparticles according to the present invention can be used in many different applications. Thus, the microparticles can be used to distribute active agents to animals or to humans in transcutaneous occlusive or semi-occlusive systems. The microparticles of the present invention are particularly suitable for use in a

occlusive patch test.

  The patch test is performed to determine whether or not a patient suffers from sensitization by contact with specific substances (allergens) or to assess the allergenic and / or irritant properties of a substance. The term "patch test" comes from the fact that from the end of the 19th century, pieces of fabric impregnated with test substances were used. Since the beginning of their use, many different types of stamps have been used. One method which has been used widely is known as the Finn chamber technique, as described in GB patent 1,459,262. In the Finn chamber procedure, the substance suspected of having allergenic or irritant properties is applied to normal skin under occlusion for a certain period of time. In case of contact allergy, this will

  therefore produce allergic eczema in the test area.

  The test substance to be applied to the skin is incorporated, for example, into petroleum jelly or, alternatively, into a solution absorbed in filter paper and is placed inside the hollow cover so as to be in contact with the surface. of the patient's skin during use. However, it has been found that during the incorporation of the allergen into a mineral fat or vaseline (VASELINE TM), the allergen is dispersed irregularly inside its support. This leads to a situation in which it is impossible to provide an exact dosage of the test substance. In addition, petroleum jelly suffers from a drawback in that its viscosity varies considerably with temperature. In hot climates, it may therefore be necessary to store it under refrigeration to prevent it from becoming too viscous. However, unless the refrigeration temperature is carefully controlled, petroleum jelly may become too solid to allow dispersion of the

  test substance, without prior heating of the petroleum jelly.

  A patch test technique as described in International Patent Application No. WO-A-8601994 employs a patch on which the test substance is preformulated in a polymer film which will swell to form a gel when the patch is applied occlusive against the skin. This technique, known as a TRUE test, solves many of the above problems in that it provides precise dosing, uniform distribution over the surface and

  high bio-availability of the test substance.

  A modification of the TRUE test method is described

  in international patent application No. WO-A-8809184.

  The invention described provides a method complementary to that described in European patent application No. EP-A-252,044. In

  these two descriptions, the allergen is incorporated into a polymer

  hydrophilic film former, such as methylated and / or propylated cellulose and similar polymers such as films made from polyvinylpyrrolidone (PVP). The manufacturing procedure described in these documents involves two steps, namely the test substance must be distributed uniformly in the film-forming material and the latter must be spread so as to form a film of uniform thickness on a suitable substrate, that is ie the film support. The exact choice of vehicle in each case will depend on the test substance and the film support used. The test substance must be able to be distributed uniformly in the vehicle. The vehicle and the film backing must be chosen so that they adhere to each other. Regarding the choice of the particular film-forming polymer and the volatile liquid which acts as a solvent for the film-forming polymer, it is imperative that they are such that the resulting gel is capable of forming a coherent film when spread. he

  It is therefore clear from these descriptions that the current method of

  formation of stamps for test, implies the taking into account of a certain number of variables, followed by several stages including a stage of film formation and a stage of film spreading. It is therefore clear that it would be desirable to have a simpler process

  to form stamps for test is.

  There are several methods for making microcapsules. The microcapsules can therefore be formed by techniques involving air suspension, coacervation, phase separation, spray drying,

  freezing, solvent evaporation and polymerization.

  The solvent is evaporated off in a liquid manufacturing vehicle (LMV). The coating material of the microcapsules, for example a polymer, is dissolved in a suitable solvent to form a coating polymer solution which is immiscible with LMV. A core material to be microencapsulated is either dissolved or dispersed in the coating material solution to form a mixture of core material / coating material. The "mixture" of core material / coating material is dispersed with stirring in the LMV to obtain the microcapsule of appropriate size. The "mixture" is then heated (in the case of a non-volatile solvent) to evaporate the solvent. In the case where the core material is dispersed in the coating polymer solution, the polymer shrinks around the core. When the core material is dissolved in the coating polymer solution, a matrix type microcapsule is formed. When all of the solvent has evaporated, the LMV temperature is reduced to room temperature (if required) while stirring is continued. At this time, the microcapsules can be used in the form of a suspension,

  deposited on substrates or isolated in the form of powders.

  As a microencapsulation process, evaporation of the solvent has many advantages over other possible forms of microencapsulation. Thus, for example, the microencapsulation process by spray drying involves the use of high temperatures. These high temperatures can have the effect of destroying or deactivating materials having pharmacological activity. In addition, there is no risk of chemical interaction between the active agent and the coating material. The monomers supplying the polymer component therefore do not come into contact at any time with the active agent, since the polymer component is added in a form already

polymerized with the active agent.

  The present invention provides a test technique

simpler epicutaneous.

  The present invention provides a microparticle comprising a polymer component and an agent having pharmacological activity, characterized in that the polymer component is a polyurethane, a substituted polyvinyl alcohol or a mixture of

  polyurethane and substituted polyvinyl alcohol.

  The microparticle of the present invention may be a matrix type microparticle. By "matrix type microparticle" is meant a microparticle comprising a mixture

  homogeneous of the polymer component of the particles and of an active agent.

  According to another aspect of the present invention, the microparticle comprises a polymer component and an agent having pharmacological activity together forming a matrix, characterized in that the polymer component is a polyurethane, a substituted polyvinyl alcohol or a mixture of polyurethane and

substituted polyvinyl alcohol.

  According to another aspect of the present invention, the agent

  pharmacologically active is allergenic.

  According to yet another aspect of the present invention, there is provided a polymer component and an agent having pharmacological activity together forming a matrix, characterized in that the polymer component is a polyurethane or substituted polyvinyl alcohol and that it does not there are no chemical bonds between the

  polymer component and pharmacologically active agent.

  The polyurethane can be slightly crosslinked.

  The present invention further provides a microparticle comprising a polymer component and an agent having pharmacological activity together forming a matrix, characterized in that the polymer component is a substantially linear polyurethane.

  not crosslinked. The polyurethane can be slightly crosslinked.

  In another aspect, the polymer component can be a substituted polyvinyl alcohol (PVA) comprising chains

hydrophobic side effects.

  According to yet another aspect of the present invention, the polymer component may comprise a blend of the polyurethane

  mentioned above and PVA polymers.

  According to yet another aspect of the present invention, the

  microparticle may additionally include petroleum jelly.

  According to yet another aspect of the present invention, the microparticle may further comprise suitable agents which enhance the penetration of the drug. Suitable agents improving the penetration of the drug are known to specialists and include oleic oil, decylmethyl sulfoxide, terpenes, dimethyl sulfoxide (DMSO), dimethylformamide

  (DMF), pyrrolidones, propylene glycol and ethanol.

  Another embodiment of the present invention provides a method of evaporating solvent to form a microparticle, the microparticle comprising a polymer component and an agent having pharmacological activity, characterized in that the polymer component is a substantially uncrosslinked linear polyurethane or a modified polyvinyl alcohol. According to the present invention, a matrix type microparticle can be formed. The agent having pharmacological activity and the polymer component which together constitute the organic phase,

  can form a solution, suspension or emulsion.

  According to a specific embodiment of the present invention, there is provided a solvent evaporation process for forming a microparticle which comprises a step of forming a suspension or an emulsion between an organic phase and an aqueous phase followed by '' an evaporation step, the organic phase being immiscible in the aqueous phase and comprising a solution of a polymer component, an active agent and a water-immiscible solvent, characterized in that the polymer component is a polyurethane or a modified polyvinyl alcohol (for example, a

substituted polyvinyl alcohol).

  According to one embodiment, the solvent evaporation method of the present invention involves the use of a core material which is dissolved in the polymer solution, which leads to

  obtaining a matrix microparticle.

  Alternatively, the organic phase may comprise a system obtained by forming a solution of the polymer component and a water-miscible solvent and subsequently adding the solution thus formed to a water-immiscible solvent. The solution

  resulting is not miscible with water.

  According to another embodiment of the invention, the organic phase also comprises petrolatum. The water immiscible solvent can be a halogenated solvent, for example, dichloromethane or trichloromethane. Preferably, the solvent

  immiscible with water is trichloromethane.

  The present invention also provides an occlusive or semiocclusive dressing comprising a covering adhesive polymer film and serving to maintain contact between the skin and the

  microparticles, and the microparticles according to the present invention.

  Alternatively, the microparticles may be dispersed throughout the polymer film, the adhesive layer, or both

film and adhesive layer.

  According to an embodiment of the present invention, the occlusive or semi-occlusive dressing can be used for a patch test on the skin (that is to say, a patch test). In another embodiment of the present invention, the occlusive or semi-occlusive dressing of the present invention can be used to deliver a transdermal drug. When the dressing is to be used as a drug delivery system, drug penetration enhancing agents may also be used.

incorporated into the dressing.

  According to another embodiment of the present invention, there is provided a patch test method, characterized in that the allergen is in microparticulate form. Examples of allergens which can be used in the present invention are given in Table 7, entitled European Standard Table of

allergens.

  The polymer usable in the present invention should not be toxic. In addition, the polymer should not react with the pharmacologically active agent, that is, it should not be able to form chemical bonds with the chemical entities of the active agent. In addition, the polymer must be stable. By

  stable, it is meant that the polymer must be stable on storage, i.e.

  say that it should not lose its activity when stored under ambient temperature conditions and protected from humidity. In a way

  similar, the active agent must be stable.

  The following components can be used to prepare the polyurethane. The polyol component can be a hydroxy-terminated polyester or a hydroxy-terminated polyether. The alkene part of the polyethers can suitably contain 1 to 4 carbon atoms. Preferred hydroxy-terminated polyethers are, for example, polyethylene glycol (PEG), polypropylene glycol (PPG) or polytetramethylene oxide (PTMO). Polyester

  preferred is a polycaprolactone diol (PCLd).

  Suitable isocyanates usable to form suitable polyurethanes in the present invention include hexamethylene diisocyanate (HDI), 4,41-dicyclohexylmethane diisocyanate (Desmodur W), isophorone diisocyanate (IPDI) or

  4,41-diphenylmethane diisocyanate (MDI).

  Suitable chain extenders which can be used are the usual chain extenders

  such as lethane diol, ethane diamine or 1,4-butane diol.

  Suitable catalysts to form the polymer

  are, for example, dibutyltin dilaurate.

  The ratio of hydroxy / isocyanate groups can be such that there is an excess of hydroxy groups. The ratio of hydroxy / isocyanate groups is therefore suitably 3: 1, preferably 1: 1. The polyurethanes which can be used in the present invention may be soluble in organic solvents which are immiscible with water. Solvents suitable for polyurethanes are therefore halogenated solvents such as chloroform. It can therefore be said that the polymers are organosoluble. In general, the polymers suitable for the present invention are non-crosslinked or slightly crosslinked linear polymers. The polymers of the present invention may be directly soluble in organic solvents

  immiscible with water so as to form a stable emulsion in water.

  The degree of crosslinking must be such that the polymers are still organically soluble. 5 g of polymer must therefore be soluble

  in 100 ml of solvent at room temperature.

  Alternatively, the polymers usable in the present invention may be such that they are not directly soluble in organic solvents immiscible with water. In these cases, the polymer can first be dissolved in a polar solvent and

  then dissolved in a water immiscible solvent.

  Table 1, entitled Synthesis of Polyurethanes, shows examples of various polyurethanes formed which are

  usable in the present invention, as shown in the table.

  The nuclear magnetic resonance (NMR) or infrared spectra can be used to characterize the polyurethanes suitable for the present invention. Molecular weight can be determined by size exclusion chromatography (SEC). Polyurethanes can therefore judiciously have a

  molecular weight in the range of about 15,000 to 350,000.

  Thus, for example, polyurethanes formed from PEG have a molecular weight of about 20,000. On the other hand, polyurethanes formed from PTMO and / or PPG have a weight

  molecular in the range of about 200,000 to 300,000.

  The polymers suitable in the present invention must not be sticky (which thus gives good separation of the particles formed from these polymers) and must not react with the active agent with which they can be brought into contact. It is preferable to use polyurethanes formed from isocyanates

  aliphatic, rather than aromatic-based isocyanates.

  As regards the polyvinyl alcohols usable in the present invention, they should ideally have the following properties. Polyvinyl alcohol must therefore be soluble in

  organic solvents, such as the solvents mentioned above.

  Polyvinyl alcohol (PVA) can be made organically soluble by grafting hydrophobic chains on the skeleton of PVA. Modified PVA or PVA derivatives should have a molecular weight in the range of about 2,000 to about 22,000 (i.e., a degree of polymerization in the range of 45 to 500 and a degree of hydrolysis in the range of about 75 to 99.5 mol%. The hydrophobic chain can have from 3 to 40 carbon atoms, a particularly preferred hydrophobic chain being the stearyl group. PVA can be substituted in a degree from 5 to 90% The degree of substitution is preferably between 10 and 50% As can be seen in Table 2, most stearyl grafted PVA polymers are insoluble in chloroform. In cases where the grafted co-polymer is PVA is insoluble in an organic solvent, it is therefore necessary to first dissolve the co-polymer in a polar solvent. Suitable polar solvents are DMF, DMSO, acetone or an alcohol such as ethanol. pol ymère grafted in the main solvent, it can be added to the secondary solvent immiscible with water, for example,

chloroform.

  To form the grafted PVA polymers, the PVA is dissolved in a polar solvent, such as DMSO. Stearyl isocyanate is then added and under certain reaction conditions, a modified graft PVA copolymer is formed. The grafted co-polymer can be precipitated by addition to water. The grafted co-polymer can then be dissolved in DMF after which the solution can be

  added and dissolved in chloroform.

  The following examples illustrate the production of microparticles of the present invention. These examples show that the aqueous phase can contain a surfactant, such as Brij 35 (polyethylene glycol dodecyl ether). It should also be noted that the organic phase may include petroleum jelly. In Examples 1 to 3, the water immiscible solvent is trichloromethane (chloroform). The process as illustrated in the following examples comprises dissolving the polymer component and the active agent component in the organic phase. This solution is then emulsified with an aqueous phase which optionally contains a steric stabilizer or a surfactant. The emulsion is obtained by mixing the organic phase in the aqueous phase at a speed in the range of 200 to 800 rpm, for example, to 600 rpm. The solvent is then allowed to evaporate by standing the solution overnight in the case of a volatile solvent, or by heating the solvent in the case of a non-volatile solvent. The microparticles thus formed can be recovered on a B chner and subjected to a washing step and a drying step. The washing step includes three washes with water. The microparticles are then dried on filter paper and placed in a desiccator for 12 hours at 50 ° C., or they

can be freeze-dried.

  The microparticles can be analyzed by light microscopy, for example, with a Leitz Wetzler microscope and by scanning electron microscopy (SEM). It has been found that the microparticles formed according to the present invention generally have a dimension of between 0.8 and 1.22 mm. However, it is also possible to form larger microparticles. It is therefore possible to form microparticles having a dimension of up to 2 mm. Microparticles smaller than 0.8 mm can also be formed according to the present invention. So for example, particles as small as 0.25mm can be formed. The size of the microparticles varies according to the ratio of the polymer component to the active agent used. The

  microparticles are generally spherical and regular in shape.

  In matrix type microparticles, the internal and external structures are porous, large vacuoles being formed inside. The polymer and the active agent, and optionally petrolatum, are completely dispersed in the matrix. It has been found that the microparticles are sensitive to pressure, the latter causing the release of the active agent. When the pressure is removed, the

  particles return to their original shape.

  The active agent can represent an amount ranging

  up to 40% of the total weight in percentage.

  The invention is now illustrated by the following examples.

Example 1

  Organic phase: solvent: CHCl3 (50 ml) polymer: polyurethane PTMO 1000 + Desmodur W (dicyclohexylmethane diisocyanate) + ethanediol (chain extender) (1/2/1) petrolatum: varying between 0 and 50% (w / p) Aqueous phase: H2O containing a surfactant, Brij 35 (polyethylene glycol dodecyl ether) (250 ml) The emulsion is produced by mixing the organic phase in the aqueous phase at a mixing speed of between, for example, 200 and 800 rpm. It should be noted, as explained above, that the polymer is already formed before mixing

  the organic phase to the aqueous phase.

  Evaporation is done at room temperature for

one night (around 4 p.m.).

  The microparticles are collected on a B chner,

washed and dried.

The average size is 1 min.

Example 2

  Organic phase: solvent: CHC13 (20 ml) polymer: polyurethane PTMO 1000 + Desmodur W (dicyclohexylmethane diisocyanate) + ethanediol (chain extender) (1/2/1) petrolatum: 0% Aqueous phase: H2O containing a surfactant , Brij 35 (polyethylene glycol dodecyl ether) (250 ml) The microparticles are formed and collected according to the

example 1 procedure.

  The average size of the microparticles is 1 min.

Example 3

  Organic phase: solvent: CHC13 (20 ml) polymer: polyurethane PEG 200 + HDI (hexamethylene diisocyanate) (10/3) vaseline: 0% Aqueous phase: H2O containing a steric stabilizer (PVA 22,000) (250 ml) The microparticles are formed and collected according to the

example 1 procedure.

  The average size of the microparticles is 1 mm.

Example 4

  Organic phase: solvents: No 1: DMF (2 ml) No 2: CHC13 (40 ml) polymer: PVA 15,000 + stearyl isocyanate)

(15%)

  petrolatum: 0 to 50% Aqueous phase: H2O containing a surfactant, Brij 35 (polyethylene glycol dodecyl ether) (250 ml) The microparticles are formed by prior dissolution of the grafted PVA polymer in DMF, then addition of the solution obtained in the chloroform. Microparticles as well

  formed have an average dimension of 20 to 50 gim.

  The Applicant has carried out a skin sensitization study to demonstrate the effectiveness of the microparticles of the present invention in determining allergenic responses. The skin sensitization study is conducted according to the Magnusson and Kligman maximization test. Allergic Contact Dermatitus in guinea pig. Charles C. Pomus page 102, 1970, Springfield, Illinois. The materials used in this study are the

  benzocaine (an allergen from the European Standard Table) and 2,4-

  dinitrochlorobenzene (DNCB). Although DNCB is not part of the standard battery of skin patch tests, it is known to be

  stimulates a 100% reaction in sensitized guinea pigs.

  The skin sensitization test is carried out according to the

  procedure described in Table 3 and as explained below.

  Macroscopic examinations are carried out on the skin,

  1h, 24h and 48h after removal of the occlusive dressing.

  Reactions are rated on a scale of 0 to 3.

  0 no visible change 1 mild erythema 2 moderate erythema 3 severe erythema and edema It is considered that animals in which the reaction is evaluated at 2 or more, after 48 hours (i.e. 24 hours after

  removal of the dressing), are sensitive.

  The sensitization rate and therefore the category of the sensitizing compound are determined by the percentage of animals which

become sensitized.

  Female Harley albino guinea pigs, weighing approximately 300-350 g at the start of the study, are used and maintained in

  precisely defined living and eating conditions.

Results

A) DNCB

  Guinea pigs are divided into three groups as follows: Group 1 (Table 4) Ten animals are sensitized with the maximum non-irritant dose of DNCB according to the protocol described in Table 3, which involves initial injections of complete Freund's adjuvant (Difco)

  diluted 50% in normal saline.

  The maximum non-irritating dose of DNCB is 1% in

  petroleum jelly applied to skin patches.

  The skin reaction is triggered by application of skin patches containing microparticles (equivalent to approximately 0.5 g of particles containing petrolatum and the active component at a concentration of approximately 1%), maintained under an occlusive dressing

for 24 hours.

  Group 2 (Table 5) Five non-sensitized control animals receive a single application of microparticle-containing occlusive patch

  DNCB under the same conditions as animals in group 1.

  Group 3 (Table 6) Five animals receive skin patch applications containing neutral particles (not containing DNCB) after injections of complete Freund's adjuvant (Difco). Two weeks later, the animals receive a second application of

neutral particles.

  Table 4 (if the result concerning the animal in which the cover dressing slipped is excluded, namely No 8), shows that an awareness rate of 88% is obtained. We can therefore classify the product as a very highly sensitizing material (class V) in a completely consistent manner with the results published for the

  DNCB which is used as the reference sensitizing compound.

  The reactions observed in the control animals fade after 24 hours, which is consistent with a

  minor irritation induced by the occlusive patch.

  As shown in Table 6, animals sensitized with neutral microparticles do not show a reaction which persists after 24 hours: the polyurethane particles containing the

  petroleum jelly therefore does not react in these animals.

  The above results indicate that neutral microparticles containing only petroleum jelly produce no reaction

  allergic, or irritant response in animals.

  It has also been shown that microparticles release the active agent in a controlled manner and do not cause the reaction

  irritant that is commonly seen with DNCB.

B) BENZOCAINE

  The guinea pigs are divided into two groups as follows: Group 1 (Table 8) Eleven animals are sensitized according to the protocol described

in Table 3.

  Table 8 shows an awareness rate of 27%.

  This is a low awareness rate, and is in complete agreement with

  published results for benzocaine.

  These results show that the polymer or the coating material of the microparticle of the present invention exerts a protective role on the skin of the animal against the allergenic molecule itself. This is a particularly result

  advantageous presented by the microparticles of the present invention.

  The Applicant has therefore shown that the microparticles of the present invention are ideally suited for determining

  whether an individual is allergenic or not to a specific allergen.

  However, it should be noted that the microparticles of the present invention provide a means of delivery for other non-allergenic active agents and that, for example, they can be used

  for the encapsulation of other active drug agents.

  Another embodiment of the present invention is an occlusive dressing used for skin patch tests comprising a film having an adhesive side facing the skin on which microparticles adhere. The occlusive film usable according to the present invention is a film as described, for example, in US patent 4,784,653. The microparticles are bonded to the film by bringing them into contact with the sticky side of the film facing the skin. These films must be continuous and provide a barrier

  against external moisture and bacteria.

  TABLE I: Synthesis of polyurethanes MDI HDI Dw IPDI BDO Solid, flexible insoluble in CHC13 PEG 200 viscous / solid solid, flexible solid, fragile +/- soluble * solid, fragile * solid, fragile CHC13 soluble CHC13 soluble CHC13 PEG 600 * solid, flexible SNR soluble CHC13 FEG viscous * solid, flexible solid, flexible 1000 soluble CHC13 soluble CHC13 * sticky solid flexible, soluble

CHC3

  PPG solid, flexible solid, flexible solid, flexible 425 soluble CHC13 * solid, flexible * solid, flexible soluble CHC13 soluble CHC13 PPG viscous viscous, transparent 4000 soluble CHC13 * viscous, white PTMO 650 solid, flexible SNR * solid, flexible soluble CHC13 PTMO sticky viscous solid, solid, flexible 1000 soluble CHC13 * solid, flexible * solid, flexible soluble CHC13 soluble CHC13 PCLd 530 viscous solid, viscous, transparent

  soluble CHC13 soluble * solid, flexible, transparent

  CHC13 soluble CHC13 PBHT * solid, flexible * flexible, yellow solid, non-sticky insoluble CHC13 insoluble CHC13 Polysiloxane HT * viscous, white * viscous, white * With ethanediol chain extender TABLE 10: PVA grafted

PVA 2000 PVA 15,000 PVA 22,000

  Iso. stearyl liquid liquid liquid% insol. CHC13, insoluble acetone. CHC13, insoluble acetone. CHC13, acetone MeOH, H2O MeOH MeOH, part. ground. DMSO hot Iso. stearyl solid solid solid 1 0% sol. DMSO warm floor. DMSO warm floor. DMSO hot insol. CHC13 insol. CHC13 insol. CHC13 Iso. stearyl solid solid solid 1 5% sol. DMSO warm floor. DMSO warm floor. DMSO hot

DMF DMF DMF

  go. ground. CHC13 leaves. ground. CHC13 insol. CHC13 Iso. stearyl solid solid solid 30% sol. DMSO warm floor. DMSO warm floor. DMSO hot insol. CHC13 insol. CHC13 insol. CHCI3 acetone acetone acetone Iso. stearyl solid solid solid 0% sol. DMSO warm floor. DMSO warm floor. DMSO hot insol. insoluble acetone. insoluble acetone. acetone leaves. ground. CHC13 insol. CHC13 insol. CHC13 Iso.stearyl solid solid solid% sol. DMSO warm floor. DMSO warm floor. DMSO hot insol. CHC13 insol. CHC13 insol. CHC13

0H2012

  Iso. stearyl solid solid solid 1 0 0% sol. DMSO warm floor. DMSO warm floor. DMSO hot insol. CHC13 insol. CHC13 insol. CHC13 Iso. n-propyl solid solid solid 75% sol. acetone, DMSO sol. acetone, DMSO sol. DMSO, EtOH EtOH EtOH insol. CHC13, 0H2012 insol. CHC13 Iso. n-propyl solid solid solid 1 0 0% sol. acetone, DMSO sol. acetone, DMSO sol. acetone, DMSO, EtOH EtOH EtOH insol. CHC13 insol. CHC13 insol. CHC13 TABLE II (continued): PVA grafted

PVA 2000 PVA 15,000 PVA 22,000

  Iso. phenyl solid solid solid 80% sol. acetone, DMSO sol. acetone, DMSO sol. DMSO, EtOH EtOH EtOH insol. acetone, CHCI3 part. ground. CHCI3 insol. CHCI3 Iso. phenyl solid solid solid% sol. acetone, DMSO sol. acetone, DMSO part. ground. DMSO CHCI3 part. ground. EtOH EtOH, THF insol. EtOH, CH2CI2 insol. CHCI3 insol. CHCI3 MAY solid solid solid% insol. CHCI3, insoluble acetone. CHCI3, insoluble acetone. CHCI3, acetone MAI solid solid solid% insol. CHCI3, insoluble acetone. CHCI3, insoluble acetone. CHCI3, acetone

TABLE 3

  Magnusson and Kligman maximization test

Experimental description

  Day 1: The guinea pigs shoulders are shaved First Day 4: Injections: step: 6 injections of 0.05 ml each, made in a rectangle of 2 x 4 cm on each side of the spine INDUCTION Injections 1 - 2 x 0 0.05 ml of Freund's adjuvant diluted (50%) in dermal physiological intra-liquid 2 - 2 x 0.05 ml of the test molecule without SENSIBILI adjuvant - 3 - 2 x 0.05 ml of the same molecule in of Freund's adjuvant Day 11: Application to the injection sites of sodium lauryl sulfate SATION 2nd stage in petroleum jelly (10%) Applications Day 12: Application of the test molecule to injection sites with topical un occlusive stamp (2 x 4 cm). The stamp is left in place for 48 hours. Day 14: Removal of stamps Break Day 21: The side of the guinea pigs is shaved

  TEST 3rd Day 25: Application of the drug with an occlusive patch (2 x 2 cm).

  step The patch is left in place for 24 hours. Day 26: Removal of the stamp

TABLE 4

  Group 1: Guinea pigs sensitized with DNCB Induced sensitization with microparticles containing DNCB No Time after removal of the patch Animal sensitization 1 h 24 h 48 h

1 2 2 1 +

2 2 2 2 +

3 2 1 1 -

4 2 2 1 +

2 2 2 +

  6 3 3 - (histology) + 7 2 2 - (histology) + 8 3 3 - (histology) + 9 1 1 1 the stamp has slipped

2 2 1 +

Awareness rate = 88%

TABLE 5

  Group 2: Animals not sensitized Only received one application of microparticles containing DNCB No Time after removal of the animal patch 1 h 24 h 48 h 1 2 1 - (histology)

2 1 1 1

3 1 0 0

4 1 1 1

1 1 1

TABLE 6

  Group 3: Animals sensitized with neutral microparticles No Time after removal of the animal patch 1 h 24 h 48 h 1 0 0 - (histology)

2 0 0 0

3 1 0 0

4 1 0 0

5 1 0 0

TABLE 7

  Annex: European standard table of allergens Name Appearance Solvent Salts Potassium dichromate S water Cobalt chloride S water Nickel sulphate S water-methanol amines Paraphenylenediamine (HC1) S water-organic Thiuram, mixture S organic Benzocaine S organic Black-rubber, mixture S Ethylenediamine (HC1) S water amino alcohols Neomycin sulfate S water-methanol alcohols, ketones, acids Quinoline, mixture S organic Rosin S organic Paraben, mixture S organic Wood alcohols 1 / 2S organic Balsam of Peru L organic Resin pt-butyl phenol -formaldehyde Formaldehyde Organic L Aroma, mixture L organic Quaternium 15 Primine sulfur Mercapto, mixture S (?) organic epoxy Epoxy resin S organic

  IN VIVO TESTS FOR MICROPARTICLES CONTAINING

BENZOCAINE

TABLE 8

  Sensitized guinea pigs No animals Time after removal of the patch Sensitization (% allergen) l h 24 h 48 h

1 (4.0) 1 1 0

2 (5.4) 2 2 - (histology) +

3 (6.4) 2 1 1 -

4 (9.5) 1 1 0 -

(8.0) 2 2 - (histology) +

6 (7.7) 1 1 1 -

7 (10.0) 1 1 0 -

8 (11.7- vas.) 0 1 1 -

9 (16.2) 1 1 0 -

(16.8) 2 1 1 -

11 (19) 2 2 1 +

Awareness rate = 27%

TABLE 9

  Guinea pigs not exposed No Time after removal of the animal patch 1 h 24 h 48 h 1 (17.2) 0 0 - (histology)

2 (23.4) 1 1 0

3 (10.6, vas) 1 1 1 (histology)

Claims (16)

  1. Microparticle comprising a polymer component and an agent having pharmacological activity, characterized in that the polymer component is a polyurethane, a substituted polyvinyl alcohol or a mixture of polyurethane and substituted polyvinyl alcohol. 2. Microparticle according to claim 1, in which the polymer component and the agent having an activity   pharmacological are not chemically related.10 3. Microparticle according to claims 1 or 2, wherein the microparticle has a matrix structure.   4. Microparticle according to any one of the preceding claims, in which the polymer component is   a practically non-crosslinked linear polyurethane. 15 5. Microparticle according to any one of the preceding claims, in which the polymer component is   a substituted polyvinyl alcohol comprising hydrophobic chains. 6. Microparticle according to any one of   previous claims, wherein the polymer component is   soluble in a water immiscible solvent.   7. Microparticle according to any one of   claims 1 to 4, wherein the polymer component is soluble in a halogenated solvent.   8. Microparticle according to any one of   previous claims, wherein the microparticle comprises more petroleum jelly.   9. Microparticle according to any one of   previous claims, wherein the active agent is allergenic.   10. A method of evaporating solvent to form a microparticle, the microparticle comprising a polymer component and an active agent, characterized in that the first component   polymer is a polyurethane or a polyvinyl alcohol derivative.   11. A solvent evaporation method for forming a microparticle comprising a step of forming an emulsion between an organic phase and an aqueous phase followed by an evaporation step, the organic phase being immiscible with the aqueous phase and comprising a solution of a polymer component, an active agent and a water immiscible solvent, characterized in that the polymer component is a polyurethane or a derivative of polyvinyl alcohol. 12. A solvent evaporation process in which a   water-miscible solvent is dissolved in the water-immiscible solvent.   13. Method of solvent evaporation according to the   claims 9 or 10, wherein the organic phase comprises more petroleum jelly.   14. Solvent evaporation process according to   Claims 11, 12 or 13, wherein the water-immiscible solvent   is trichloromethane or dichloromethane.   15. Occlusive dressing used for skin patch tests, comprising a film having an adhesive side facing the skin on which adhere microparticles containing the active agent pharmacologically.   16. Patch test method, characterized in that   the active agent is incorporated into a microparticle.